Concrete slab joint construction

ABSTRACT

A CONSTRUCTION FOR JOINTS BETWEEN CONCRETE SLABS THAT ALLOWS THE ADJACENT SLABS TO SHRINK WITHOUT CRACKING THE SLABS OR DESTROYING WALL STRUCTURES OR OTHER DEVICES THAT MIGHT BE RIGIDLY MOUNTED TO SUCH SLABS. THE JOINT IS SO DESIGNED THAT IT IS REINFORCED AND SELF-SUPPORTING AND ALLOWS OTHER CONSTRUCTION WORK TO CONTINUE WHILE THE NORMAL SHRINKAGE IS TAKING PLACE.

Jal!- 19, 14971' c. R, MAG'ADINI j 3,555,753

`CONCRETE SLAB 'JOINT CONSTRUCJIONk Filed sept. 49, 1968 2 sheets-sheet 1 vFigf I4)- INVENTOR.

Charles R. Magadini- Jan. 19, 1971 .K "c, R. MAGADINI A 3,555,753

CONCRETE SLAB JOINT CONSTRUCTION I I Filed sept. 1968 4 '2'-sheetssneet 2 Fig C m' N l2 C 24 /4/ Fig. `6 ls) $9 4Q a l Char/es R. Magadlni lNI/IiNTOK.

United States Patent C) 3,555,753 CONCRETE SLAB JOINT CONSTRUCTION Charles R. Magadini, 1133-A E. Missouri Ave., Phoenix, Ariz. 85014 Filed Sept. 9, 1968, Ser. No. 758,469 Int. Cl. E04b 5/32; E04c 2/04 ILS. Cl. 52--227 11 Claims ABSTRACT OF THE DISCLOSURE A construction for joints between concrete slabs that allows the adjacent slabs to shrink without cracking the slabs or destroying wall structures or other devices that might be rigidly mounted to such slabs. The joint is so designed that it is reinforced and self-supporting and allows other construction work to continue while the normal shrinkage is taking place.

In the construction of buildings concrete slabs of great longitudinal dimensions are a common occurrence. These elongated slabs are usually roof or lioor slabs which are suspended or supported on columns and walls and, being the horizontal surfaces of building structures, are usually completely enclosed by and attached to exterior walls. Such being the case, problems arise since it is a peculiarity of concrete that as it cures and hardens it undergoes a left to provide an area to compensate for the shrinkage r and were lled with concrete once a reasonable amount of time has been allowed for the shrinkage to occur. This is highly undesirable, as the edges of the joint must be supported and the joint itself impedes further construction work which usually results in the joint being filled with concrete before the measured percentage of the totalL slab shrinkage has taken place.

The present invention relates to a joint construction for concrete slabs that allows the shrinkage to take place conveniently with the edges of the slabs interconnected to lend support to one another as well as doing away with the Wide gap or joint normally associated with such construction. The joint provides for reinforcing rods to extend across the joint thereby tying the joints together to support them therebetween. The reinforcing bars are arranged such that they form a hinge point between the panels thereby further reducing stresses that may occur due to relative vertical movement between the slabs.

Further, a sheathed cable is mounted in one slab and exnumerals refer to like parts throughout, and in which:

FIG. 1 is a top plan view, with a section broken away for clarity, of a concrete slab incorporating the subject joint.

FIG. 2 is a sectional view taken substantially along the line 2-2 of FIG. 1.

FIG. 3 is a sectional view taken substantially along the line 3--3 of FIG. 2.

Patented Jan. 19, 1971 ICC FIGS. 4 through 7 are sectional views showing the steps in the construction of the subject joint.

FIG. 8 is an enlarged sectional View of the tensioning end of the sheathed cable.

Referring now to the drawings, the reference numeral 10 generally indicates the subject joint which is between a first concrete slab 12 and a second concrete slab 14. The joint construction 10 includes a series of reinforcing rods 16 and a plurality of sheathed tensioning cables 18.

The reinforcing rods 16 are bent into a predetermined shape which includes a iirst horizontal section 20 which is connected to an angular intermediate section 22 which in turn is connected to a second horizontal section 24 which is parallel to the first horizontal section 20. The sheathed tensioning cables 18 comprise an elongated sheath 26 which has a cable 28 extending therethrough with the cable having an anchor plate 30 fixed to one end thereof and a second anchor plate 32 adjustably fixed to the other end thereof. The anchor plate 32 has a cone-shaped opening 34 through the center thereof which receives the cable 28 therethrough. A cone-shaped chuck 36 of a cross-section to cooperate with the cone-shaped opening 34 is received over the cable 28 to provide for tightening of the cable 28 by drawing the cable through the chuck 36 and then allowing the wedging action between the opening 34 and chuck 36 to tighten the chuck around the cable.

To utilize the joints in the construction of large slabs, the end 38 of a slab 12 is formed with a triangular notch 40 along its entire width. The angle which the intermediate angular section 22 of the reinforcing rods makes with the horizontal sections 20 and 24 thereof, is chosen so that when the concrete slab 12 is formed the angular section 22 will extend through the form and lie along the angled sides of the triangular notch 40 with the horizontal sections 24 extending perpendicular to the end of the sla-b 38. Similarly, one half of the sheathed tensioning cable 18 is embedded in the concrete slab 12 and extends through a hole in the form for the slab so that the sheath will exit the slab at the apex of the triangular notch 40. Thus, when the forms are removed the structure will be as shown in FIG. 4. As shown therein, a pair of reinforcing rods 16 have been placed so that the rst horizontal sections 20 are parallel to one another and spaced there apart so that the angular sections 22 thereof, as mentioned above, exit the concrete slab and are juxtaposed with the sides of the triangular notch 40, with the second horizontal sections 24 ybeing perpendicular to the end 38 of the slab at the point where the triangular notch is cut into the end. The sheathed tensioning cable is shown as mounted in the center of the slab 12 with the anchor plate 30 embedded in the concrete and the sheath 26 and cable 28 exiting the slab at the apex of the triangular cutout 40. At this point, the forms for the second concrete slab to be juxtaposed with the first slab 12 are put in place. The forms for the second sla-b 14 are constructed with a block out such that a cavity 42 will occur in the concrete slab. The horizontal sections 24 of the reinforcing rods are embedded in the slab 14 with the sheath 26 and cable 28 extending perpendicularly out of the base of the cavity `42 with the second anchor plate 32 mounted on the sheath and cable at the face thereof. Thus when the forms are removed from the second concrete slab 14 the structure will be as shown in FIG. 5, wherein the concrete sla-bs 12 and 14 are juxtaposed with the reinforcing rod assemblies 16 embedded therebetween providing support therefor, and the sheathed cable assembly 18 extends from the lirst slab 12 into the second slab 14 and out of the cavity 42 with the second anchor plate embedded as set forth above. With the slabs 12 and 14 as set up in FIG. 5 the formation of the joint is complete and the concrete may then be allowed to set or cure. As

the concrete in the slabs 12 and 14 cures the slabs will shrink and separate leaving a gap 44 as shown in FIG. 6. As the gap 44 gradually increases the angular intermediate sections 22 of the reinforcing rods will attempt to assume a straight line between the points where they enter the slabs 12 and 14. Similarly, the cable 28 will be drawn into the sheath 26 as the slabs 12 and 14 separate. In this Way the shrinkage of the slabs 12 and 14 can be accommodated without fracture or cracking of the slabs thus joined together. Also, since the slabs 12 and 14 are cast in abutting relation, the separation 44 will not be so great as to cause a hindrance in the rolling about of equipment or in completing other construction projects thereon. Further, since the gap 44 is so slight as compared to the extremely wide gaps normally left in such construction, the joint can be left open for a longer period of time thus assuring that the majority of the shrinkage due to curing of the slabs has occurred. When it has been determined that the acceptable amount of shrinkage has occurred in the slabs 12 and 14, the gap 44 left between the slabs is filled with grouting 46 to seal up the gap thus left. When the grouting has set the cable 28 is withdrawn through the sheath to exert a tension load thereon and draw the slabs 12 and 14 together thereby placing the grouting 46 under pressure. When the proper load has been exerted on the cable 28 the cone-shaped locking chuck 36 is secured in place thereby maintaining the load on the cable and the grouting 46. With the grouting thus poured in place and under tension provided by the cable 28 the joint is complete.

The structure as set forth hereinabove and the method for utilizing it in the joining of concrete sla-bs can readily be seen as a distinct advance over presently practiced methods in such joints. The drawings disclose the use of a pair of reinforcing rods 16 in conjunction with a sheathed tensioning cable 18 therebetween. However, as can be realized the number and placement of the reinforcing rods 16 and sheathed tension cables 18 is optional and would depend upon the predicted loads that the joint would have to bear. Also they could be spaced across the entire width of a joint, or concenrated in certain areas of higher loading. The joints are extremely functional and do not inhibit the progress of other work on the buildings wherein the joints are utilized. Further, while the structure and method set forth hereinabove has been shown applied to a solid concrete slab, it can be readily seen that the construction is adaptable to the waffle-type slabs or any of the other voided concrete slabs currently in use whether they be installed on grade or supported in the air. The construction can also be seen to be adaptable wherever two poured in place concrete slabs abut and shrinkage occurring will cause stress loads and resultant cracking therein.

What is claimed as new is as follows:

1. A joint construction for concrete slabs, comprising:

a first concrete slab, a second concrete slab, and means interconnecting said slabs to provide support therebetween and to permit limited relative longitudinal movement therebetween, said first concrete slab having a V-shaped notch in one side thereof and said second slab having a cooperating V-shaped abutment to be received in said notch, said means including at least one reinforcing rod and at least one tension element, the reinforcing rod having a first horizontal portion, an intermediate section connected at one end to said rst portion at an angle thereto, and a second horizontal portion connected to the other end of said intermediate portion in parallel relation to said first portion, the first horizontal portion of the rod being embedded in the first slab, the intermediate section of the rod being aligned with a leg of the notch with half of said section embedded in said first slab and the other half of said section lying on the surface of the leg of said notch between the cooperating notch and abutment, and the second horizontal portion of the rod embedded in said Second slab.

2. The device of claim 1 wherein a plurality of rods are embedded with adjacent rods being rotated from one another about an axis parallel to said first and second portions so that the intermediate sections align with opposite legs of the V-shaped notch and cooperating abutment.

3. The device of claim 1 wherein said tension element comprises a tensionable cable, an anchor attached to one end of said cable, said anchor and said one end of said cable being embedded in the first slab, and adjustable anchor means on the second end portion of said cable, said adjustable anchor means and said second end portion of the cable being embedded in said second slab.

4. The device of claim 3 wherein said cable emerges from said first slab at the apex of the notch and enters the second slab at the apex of the abutment thereon.

5. A joint construction for concrete slabs, comprising: a first concrete slab, a second concrete slab, and means interconnecting said slabs to provide support therebetween and to permit limited relative longitudinal movement therebetween, said first concrete slab having a V-shaped notch in one side thereof and said second slab having a cooperating V-shaped abutment to be received in said notch, said means including at least one reinforcing rod and at least one tension element, said tension element comprising a cable, a sheath surrounding said cable, an anchor attached to one end of said tension element, and anchor means adjustable along the other end of said tension element, said anchor and said one end of said tension element being embedded in the first slab and the other end of said tension element being embedded in said second slab, said tension element emerging from said first slab at the apex of the notch and entering the second slab at the apex of the abutment thereon.

6. The device of claim 5 wherein said other end of said tension element emerges from said second slab so that the cable may be withdrawn therefrom thereby tending to draw said slabs together, and said cable locked in the withdrawn position therefrom by the adjustable anchor means.

7. A joint construction for concrete slabs, comprising: a first concrete slab, a second concrete slab, and means interconnecting said slabs to provide support therebetween and to permit limited longitudinal movement therebetween, said first concrete slab having a notch in one side thereof and said second slab having a cooperating outwardly projecting abutment receivable in said notch, said means interconnecting said slabs including at least one reinforcing rod, said reinforcing rod having a first horizontal portion embedded in the rst slab, an intermediate section connected at one end to said first rod portion at an angle thereto and extending along a surface of the notch from the inner end thereof to the outer end thereof between the notch and the abutment, and a second horizontal portion connected to the other end of the intermediate portion in laterally spaced generally parallel relationship to said first portion, said second horizontal portion being embedded in said second slab.

8. The device of claim 7 wherein the inner end of said notch is defined by a pair of angularly related faces, the intermediate section of said rod extending through the angle defined by said faces. v

9. The device of claim 8 wherein a plurality of rods are embedded with adjacent rods being rotated approximately 180 from one another about an axis parallel to said first and second portions, whereby the intermediate sections of the rods extend angularly along opposed faces of the notch between the notch and the cooperating abutment.

10. A method for joining concrete slabs, comprising: forming a first concrete slab with a notch along one side thereof, embedding reinforcing rods in said first slab to emerge from said slab and lie along the sides of said notch, bending the portion of said rods beyond the notch to be perpendicular to said one side, embedding tension elements in said rst slab so that the free ends thereof emerge at the inner end of said notch, forming a second concrete slab with an abutment on one side thereof to engage said one side of said first slab and notch therein, embedding the perpendicular portions of said rods in the second slab, embedding said free ends of said tension elements in said second slab so that they enter thereinto at the outer end of said abutment and emerge therefrom from a surface of said second slab, and installing adjust able anchor means on the free ends of the tension elements to draw said elements therefrom and exert a tension in said elements to thereby draw said slabs together.

11. A method for joining concrete slabs, comprising: forming a first concrete slab with a V-shaped notch along one side thereof embedding reinforcing rods in said first slab to emerge from said slab and lie along the sides of said notch, bending the portion of said rods beyond the notch to be perpendicular to said one side, embedding tension elements in said irst slab so that the free ends thereof emerge at the apex of said notch, forming a second concrete slab with a V-shaped abutment on one side thereof to engage said one side of said first slab and V-shaped notch therein, embedding the perpendicular portions of said rods in the second slab, embedding said free ends of said tension elements in said second slab so that they enter thereinto at the apex of said abutment and emerge therefrom perpendicular to a surface of said second slab, and installing adjustable anchor means on the free ends of the tension element to draw said element therefrom and exert a tension in said elements to thereby draw said slabs together.

References Cited UNITED STATES PATENTS 1,505,174 8/1924 Triol 94-8 2,413,990 1/ 1947 Mantz 52-223 2,538,443 1/1951 Delvaux 52-229 2,833,186 5/1958 Dobell 52-223 2,917,901 12/ 1959 Lackner 52-223 2,921,354 1/1960 Pankey 94-8 3,182,109 5/ 1965 Greulich 52-223 FOREIGN PATENTS 912,071 1962 Great Britain 94-8 HENRY C. SUTHERLAND, Primary Examiner U.S. Cl. X.R. 52-432, 593, 747 

